"Giant Green Anemone" (Anthopleura xanthogrammica)
Also known as the Green Surf Anemone, Green Anemone, Solitary Anemone, Rough Anemone, and the Giant Tidepool Anemone, Anthopleura xanthogrammica is a species of Actiniid sea anemone that inhabits low to mid intertidal zones in the Pacific Ocean, ranging from Alaska to Southern California and rarely down to Panama. Like other sea anemones A. xanthogrammica sports several nemoatocyst lined tentacles which are used to paralyze and capture prey that wanders too close. Phoyosynthetic algae of the genus Zoochlorella and dinoflagellates of the genus Symbiodinium live in the tissue and gut of A. xanthogrammica, in this symbiotic relationship they will provide nutrients to the anemone via photosynthesis (partly giving the anemone its green coloration) and in turn they get a safe place to reside.
Image: Stan Shebs